Climate-driven heat peaks may shrink wheat crops

January 29, 2012
by Marlowe Hood

Drought-stricken wheat crops bake in the sun in 2011 near Hermleigh, Texas. More intense heat waves due to global warming could diminish wheat crop yields around the world through premature ageing, according to a study published in Nature Climate Change.

More intense heat waves due to global warming could diminish wheat crop yields around the world through premature ageing, according to a study published Sunday in Nature Climate Change.

Current projections based on computer models underestimate the extent to which hotter weather in the future will accelerate this process, the researchers warned.

Wheat is harvested in temperate zones on more than 220 million hectares (545 million acres), making it the most widely grown crop on Earth.

In some nations, the grain accounts for up to 50 percent of calorie intake and 20 percent of protein nutrition, according to the International Maize and Wheat Improvement Center (CIMMYT), near Mexico City.

In 2010, drought and wildfires in wheat-exporting Russia pushed world prices of the grain to two-year highs, underscoring the vulnerability of global supplies to weather- and climate-related disruptions.

Greenhouse experiments have shown that unseasonably high temperatures -- especially at the end of the growing season -- can cause senescence, the scientific term for accelerated ageing.

Fluctuations in wheat yields in India have also been attributed by farmers to temperature, most recently a heat wave in 2010 blamed for stunting plant productivity.

An Indian farm labourer uses a scythe to harvest wheat in a field on the outskirts of Amritsar in 2011. More intense heat waves due to global warming could diminish wheat crop yields around the world through premature ageing, according to a study published in Nature Climate Change.

To further test these experiments and first-hand observations, a trio of researchers led by David Lobell of Stanford University sifted through nine years of satellite data for the Indo-Ganges Plains in northern India and then used statistical methods to isolate the effects of extreme heat on wheat.

They found that a 2.0 Celsius increase above long-term averages shortened the growing season by a critical nine days, reducing total yield by up to 20 percent.

"These results imply that warming presents an even greater challenge to wheat than implied by previous modelling studies, and that the effectiveness of adaptations will depend on how well they reduce crop sensitivity to very hot days," the researchers concluded.

The world's nations, under the UN Framework Convention on Climate Change (UNFCCC), have said that Earth's average temperature should not exceed the preindustrial benchmark by more than 2.0 C if dangerous warming impacts are to be avoided.

On current trends -- absent a major reduction in the emission of heat-trapping greenhouse gases -- the global thermometer could rise by twice as much, according to scientists.

"Even changes that were once considered rather extreme scenarios, such as a 4.0 Celsius (7.2 Fahrenheit) increase in global mean temperature, ... could happen as soon as the early 2060s," the study notes.

Wheat also faces another possibly climate-related threat: aggressive new strains of wheat rust disease have decimated up to 40 percent of harvests in some regions of north Africa, the Middle East and Central Asia.

Wheat rust is a fungal disease that attacks the stems, grains and especially the leaves of grains including wheat, barley and rye.

Global warming and increased variability of rainfall have weakened the plants even as these emerging rust strains have adapted to extreme temperatures not seen before, scientists say.

In November, the UN's climate science panel concluded that man-made climate change has boosted the frequency or intensity of heat waves, and that such extreme weather events are virtually certain to increase in the future.

If greenhouse gas emissions continue unabated, one-in-20-year heat peaks would likely occur every five years by about 2050, and every year or two by the end of the century, the Intergovernmental Panel on Climate Change (IPCC) said in a 1,000-page report.

Researchers meeting at a scientific conference in Aleppo this week reported that aggressive new strains of wheat rust diseases  called stem rust and stripe rust  have decimated up to 40% of farmers' wheat fields ...

Global warming is likely already taking a toll on world wheat and corn production, according to a new study led by Stanford University researchers. But the United States, Canada and northern Mexico have largely escaped the ...

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22 comments

When will the deniers wake up? Scientists and responsible news outlets report on all sorts of proof of Climate Change and Global Warming many times a day, all over the internet, TV, print and radio. Deniers have run out of any credible arguments. Money can only buy the Bull Hockey, but with so much Truth flying around constantly, smart people aren't falling for Big Oil and Big Business' Lie Fest, supported by most of the GOP in the U.S.A.anymore. Sure, devoted Fox News brainwashed keep marching out of step with Reality, but with enough intervention by concerned friends and family, we can deprogram some of them. We do need to expose, once and for all, the constant lie fest of Fox News, on more than the Daily Show with John Stewart. But, at least I know what is what. Small comfort, if the liars keep winning more gullible converts, resulting in a runaway Green House Effect. That will end life as we know it on Earth. Let's not let stupid win.

Forget global warming - it's Cycle 25 we need to worry about (and if NASA scientists are right the Thames will be freezing over again) * Met Office releases new figures which show no warming in 15 years

Just for the record, Paul, there is no "runaway Green House Effect". Not even on Venus, which is where the term was invented for.

The most powerful and vocal deniers have something to materially to gain from their position. Deniers have an agenda and that is quite simple, it's selfishness. They simply lack compassion and this isn't so much a moral failing as it is an evolutionary necessity to survive while others perish.

Because of this reason, and many many others, I don't see humanity adapting to climate change. There will be a massive die-off in human population. This is unfortunate but in many ways a necessary step in societal evolution.

Because of the internet the deniers behavior and their effects can be easily studied by later generations. Let's hope that this will engender the general populace with an increased understanding of how to combat those that put self interest before the human race.

What is frightening about the fraudsters that promote the CAGW / CO2 doom and gloom model theory would they have us go back in time to 280ppm of CO2 would they prefer a cold world say 0.8°C cooler?

If we have dangerous warming and the global temperature has increased by 0.8°C since the Little Ice Age, does this mean that the ideal temperature for life on Earth is that of the Little Ice Age? During the Little Ice Age, people and all life forms died from starvation and cold, the economies of the world suffered, it was not a good time to be on Earth. Besides the cold, there were crop failures, famine, warfare and disease. Yes that's really something to look forward to again!!

re: http://www.dailym...ain.html It may pay to note that we have been in a la nina cycle for two years now (which is unusual in its self) and only expected to start entering into the el nino in the next few months so the line on that temp graph is going to start heading straight back up.

Conclusion: "If greenhouse gas emissions continue unabated, one-in-20-year heat peaks would likely occur every five years by about 2050, and every year or two by the end of the century, the Intergovernmental Panel on Climate Change (IPCC) said in a 1,000-page report."

That is the part of the article you deniers need to contend with. The UN's IPCC has far more credibility than all of you combined. As a wheat guy from the SW of KS, I can tell you personally how critical the Late July, Aug weather is for the harvest. It's not pretty now. The farmers know it. They live and die by the weather and the global disruption caused by that global average 0.8C rise is of real concern and will have real consequences on the markets and the economy.

"One of the worst droughts in Texas history began in the winter of 1950 and continued throughout the decade. In 1955 a combination of extreme drought and infestation reduced the annual yield of wheat to only 14,326,000 bushels.""In 1961 Texas wheat acreage yielded 86,956,000 bushels, the third largest crop on record. ""The size and value of the crop decreased in 1969 and 1970"http://www.tshaon...es/afw01Roughly a 10 year cycle. The sun has an 11 year cycle.

"the political left have everything to gain by supporting cataclysmic AGW." Back that up with some real facts and perhaps you'll make a convert to your religion.

AGW is not a religion. It's just what is happening to the Earths environment that is causing all of the unusual storms, droughts, temperature rises, methane releases, acidic oceans ... all because of extreme CO2 from humans burning fossil fuels.

"the political left have everything to gain by supporting cataclysmic AGW."

Back that up with some real facts and perhaps you'll make a convert to your religion.

Social engineering, and redistribution of wealth are right up the political lefts ally, by definition, and such things are proposed all the time as "solutions", by UN and environmentalists who tend to be left leaning.

AGW is not a religion. It's just what is happening to the Earths environment that is causing all of the unusual storms, droughts, temperature rises, methane releases, acidic oceans ... all because of extreme CO2 from humans burning fossil fuels.

That is the theory, yes. My problem with it is the borderline fraudulent precision that is claimed of a few tenths of one degree per few decades, and the speculation that AGW added '5 mph to hurricanes', and the frequent citing of particular weather events as being caused worse by AGW. That is wild speculation.

There is no way climate scientists have such a handle on something so messy as global climate to the degree of accuracy they claim. That said, I think it's a good thing to move off of dirty energy sources, as long as it is done in accord with existing economies, and western governments don't turn socialistic in the effort.

Hi Noumenon. You make a good argument. I'm not that paranoid about a few 10ths of a degree, but recognize that is 0.8C or (1.44F for US) is a global average. 1.44F (0.8C) is HUGE! Obviously weather temps fluctuate all over the place as we saw this past summer in TX, KS hottest ever summer and the coldest places ever which didn't occur.

All across the middle latitudes this years, how un-seasonably hot is it? I saw a story from IN where they were going to be 65F tomorrow, Jan 30th. Is this years Superbowl going to be the ultimate sweat-bowl?

Thats not due to solar cycles. It is obviously due to something changing the weather patterns GLOBALLY, and as the ice caps melt it will effect us PERMANENTLY.

I disagree with you, I think the climate scientist actually do have a pretty good handle on what is going on, and we have a good idea of how much CO2 we need to reduce; 25 billion tons/Yr. (FYI: all the volcanoes on Earth only produces 2 million tons/yr of CO2).

It's just what is happening to the Earths environment that is causing all of the unusual storms, droughts, temperature rises, methane releases, acidic oceans ... all because of extreme CO2 from humans burning fossil fuels.

It was so funny reading your reply @Shelgeyr. Just place your hands over your ears and just say "lie, lie, lie, lie". I kept laughing and laughing. What a clone you are.

AGW is science. Also the website you so proudly drug up from the mud is 100% BS and has no credibility. The website is biased and theirs a graphs are wrong. Leave it to someone with a pathological skeptic disorder to bring it up.

So... I suggest you go to NASA, read the reports there. Look at a paper or two from 'Nature' and get some sleep. If you believe the website you reference, you have been played.

How can this be science when the AGWites have already concluded humans are the ONLY cause for global warming? Science is a process of hypotheses, data collection, hypothesis rejections, new hypotheses, more data, ....AGWites are believers, not scientists.

AGW is only caused by Humans burning fossil fuels R2. Here is a stat; all of the volcanic systems on the globe creates barely 25 million tons of CO2/year. Our population centers, the cars, industry, electricity and home heating releases like 35Billion tons of CO2/year all from released sequestered CO2. Those are facts.

Science is a human process and as with all things human, stuff can go wrong. However the process of discovery, the finding of facts, and drawing conclusion through deduction and reason is the foundation of science. Cause and effect. Cause and effect.

I'm a science guy and every piece of evidence seems to indicate AGW (Anthropogenic Global Warming ie: Manmade pollution) is the cause of global temperature rise. That's not religion; that is just common sense. Question for you R2, are you a Pathological Skeptic?

The article was more about wheat crops being affected and less about global warming and man's impact on global warming and the planets. There are other threads of discussion that one can expound on these issues. What is important to recognize is that heat has an effect on wheat in other ways. Any farmer will tell you that thermal dynamics and the study of, as it relates to thier crops, is an ever growing field of scientific study, regarding maintaining the "nutrient value" of their crop. Companies that mill this wheat will also tell you of the delicate processes involved to maintain the nutrient value when processing this wheat into flour. The nutrient value is lessoned and they have to "enrich" the flour. The methods used in these mills and the temperatures used are much lower than the temps we use in the kitchen. By the time that flour is made into dough or pasta the nutrient content is extremely low if present at all.And then we cook the stuff. Cooking temps destroy whats left